Cloth cutting machine



Feb. 25, 1936. M. ZAWISTOWSKI 2,031,626

CLOTH CUTTING MACHINE Filed Feb. 14, 1955 T INVENTQR Mariam ZawzsiawszaATTORNEY5 v Patented. Feb. 25, 1936 UNITED STATES PATENT OFFICE 7Claims.

Cloth cutting machines of the general type shown in my prior Patents1,378,162 and 1,568,- 705, usually comprise a supporting base adapted tobe advanced along the cutting table and. be-

neath the layers of material to be cut, and a kn1fe havingits upper endconnected to a power driven crosshead or other suitable member toreciprocate the knife. It is important that the knife be so mounted inrespect to the crosshead that its lower end, at the end of thedownstroke, will not hit the operating table or the base, as suchhitting will cause the machine to jump, will injure the operating table,or will injure or break the knife.

It is frequently necessary to remove the knife to sharpen it or toinsert a new one. For that purpose it is desirable that the connectionbetween the knife and the crosshead be such as to permit the slipping ofthe knife lengthwise through the base in or out of position when thelocking screw is loose.

Hitherto, the upper end of the knife has been provided with anopen-ended elongated slot for receiving the locking screw or bolt, theslotted part being freely slidable along the screw while said screw wasloose. With such a construction there is no assurance that the knife isin any desired relative position with respect to the crosshead when thescrew is tightened.

One object of the present invention is to provide a. cloth cuttingmachine in which the locking of the knife cannot be effected unless theblade is in a predetermined position with respect to the crosshead andin which the knife may be slipped lengthwise with respect to thecrosshead when the locking member is loose.

Another object is to provide a knife having its upper end so constructedas to insure the attachment of the knife in predetermined position withknife to be removed by moving it lengthwise with respect to a crossheadand. without removing. the locking member. s

In carrying out my invention, I provide one end of the knife with anopen-ended elongated slot extending lengthwise thereof and. having meansautomatically operable upon the tightening or clamping rotation of thelocking screw for moving the knife lengthwise into predeterminedposition with respect to the crosshead. For that purpose, one of thefingers or prongs forming a side of the slot has a series of inwardlyextending rack teeth adapted to mesh with a pinion connected to thelocking screw. The distance from the crowns of the rack teeth to theinner side respect to the crosshead while permitting said.

of the adjacent prong is smaller than the maximum diameter of the pinionso that lengthwise movement of the knife cannot be effected withoutturning the locking screw. The bottom rack tooth is spaced at such adistance from the base of the slot that the pinion when seated in thebase of said slot may be rotated without interference from the rackteeth.

In mounting the knife in position it is moved lengthwise until the outerends of the prongs are underneath the screw head. The screw is thenturned in a tightening direction, this move ment causing theintermeshing of the pinion with the rack teeth so that the knife ismoved in- Wardly towards the crosshead. This movement continues untilthe pinion lies in the base of the slot. In this position, the rotationof the screw can be continued until the knife has been clamped to thecrosshead.

Since the rack teeth must be on that side of the knife which will permitthe movement of the knife towards the crosshead when the screw is turnedinto tightened position, it is seen that if the knife were reversed, thetightening rotation of the screw would not cause the pinion to mesh withthe rack teeth but would tend to eject the knife from the crosshead sothat the operator will instantly note that the knife is being mounted inreversed position.

In the accompanying drawing, there is shown for the purpose ofillustration, one embodiment of the present invention. In the drawing:

Fig. 1 is a vertical section of part of a cloth cutting machine,

Fig. 2 is a section taken on the line 2-2 of Fig. l, I

Fig. 3 is a section taken on the line 33 of Fig. 2, and

Fig. 4 is a side view of one end portion of my improved knife.

The working parts of the machine illustrated are carried by a verticallydisposed stand l0 connected at its lower end to a base ll adapted toadvance along a table and underneath the layers of material to be cut asit is guided to follow the pattern or desired line. The upper portionsof the machine are not shown but may be of any suitable construction,for instance such as that illustrated in my prior Patents 1,378,162 andIn these prior constructions, there is crosshead I4 which is verticallyslidable in guides I 5 formed in the frame structure of the machine.This crosshead is shown as having substantially V-shaped opposite edgesengaging and slidable along corresponding V-shaped guideways in theguides I5. Connected to the crosshead is a reciprocatory knife I6 whichis vertically movable in a slot or groove in the front edge of thestandard I0. In front of this knife I6 is a vertically adjustable memberI! having at its lower end a presser foot I8, this pressed foot havingfingers 20 engaging opposite sides of the knife and serving as a knifeguard. The base II may have a throat plate 2| presenting a narrow slit22 onto which the lower end of the knife may enter at the end of itsdown stroke. The crosshead I4 has an extension 24 and a groove 25 topermit the attachment of the knife I6 to the inner side of the extension24 and to receive the upper end of the knife. The upper end of the knifeI6 is provided with an open-ended elongated slot 26 extending lengthwisethereof and forming a pair of prongs or fingers 21 and 28.

As an important feature of the present invention, the knife I6 is soconstructed as to permit the locking of the knife to the crosshead I4only when the knife is in a predetermined position with respect thereto.

As shown, the prong 21 is formed with a plurality of inwardly extendingteeth 30 so as to form a rack bar. For locking the plate in positionthere is provided a locking screw or stud 3| having ahead 32 adapted toreceive a suitable turn ing tool. Adjacent to the inner side of the head32 is a pinion 33 and beyond said pinion is a reduced threaded extension34 adapted to be threaded into a hole 35 in the crosshead I4.

The distance between the crowns of the teeth 30 and the facing edge ofthe prong 28 is smaller than the maximum diameter of the pinion 33, butis sufficiently wide so that upon turning the locking screw 3| in aclockwise direction for a right-hand screw (as viewed in Fig. 3) theteeth of the pinion 33 will mesh with the teeth 33 of the prong 21 andwill cause the lengthwise movement of the knife towards the crossheaduntil the pinion lies in the base of the slot 26.

The base of the slot 26 may have a curvature corresponding to the crowncircle of the pinion 33 and the bottom rack tooth 30 is sufficientlyspaced above the base of the slot 26 so that the pinion 33, when in itslowermost position in the slot, will be free to rotate therein withoutinterference from the teeth 30 as shown in Fig. 3. The hole 35 has athreaded portion to receive the stud 34 and its inner side has a socketto receive the pinion 33 when the screw 3I is in clamping position.

The stud 3I is advantageously enlarged at the extremity of the threadedportion to prevent the stud from being unscrewed too far from thecrosshead. For that purpose, a washer 36 may be welded to the end of thethreaded extension 34. This washer or other enlargement serves not onlyto limit the extent of unscrewing of the stud so that the pinion 33 willextend between the prongs 21 and 28 in the loose position of the stud,but also serves to prevent the stud from extending to a loose positionwhere it would break the machine if the motor were to be inadvertentlystarted.

In the mounting of the knife in position, the upper ends of the prongs21 and 28 are placed against the inner face of the crosshead extension24 and slipped underneath the stud head 32 until the upper tooth 33 isin mesh with the teeth of the pinion 33. A suitable turning tool isapplied to the stud head 32, the rotation of which causes the lengthwisemovement of the knife inwardly towards the crosshead I4 until the pinionlies in the base of the slot 26. Further rotation of the stud 3| causesthe knife to be clamped between the stud head 32 and the crossheadextension 24. If the stud has a right-hand thread, the teeth 36 must beon the left-hand side as viewed in Fig. 3. If the knife is reversed sothat the teeth are on the right-hand side as viewed in Fig. 3, theclockwise turning of the stud 3I would tend to eject the knife away fromthe crosshead. By means of this construction, not only is the knife I6locked in a predetermined lengthwise position with respect to thecrosshead I4 but the mounting of the knife I6 with the lower cuttingedge extending in the right direction, is assured.

In order to permit the knife to'be used with other machines which arenot provided with pinions for effecting the movement above referred to,the base of the slot may have a recess 31 in which a clamping bolt of adiameter less than the distance between the teeth 30 and the prong 28,may seat.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:-

1. A cloth cutting machine including a knife, a crosshead adapted to bereciprocated, and means including a rack and a pinion between saidcrosshead and the upper end of said knife for moving the knife to, andassuring the looking of the knife in predetermined position with respectto said crosshead.

2. A cloth cutting machine including a crosshead, a reciprocatory knifehaving an elongated slot extending lengthwise at one end thereof, ascrew member in said slot for locking said knife to said crosshead, andmeans whereby said screw member can lock said knife to said crossheadonly when said knife is in a predetermined lengthwise position withrespect to said crosshead.

3. A cloth cutting machine including a crosshead, a reciprocatory knife,a screw member, and means for moving said knife lengthwise with respectto said crosshead in response to the tightening rotation of said screwmember, said means permitting the clamping of said knife onto saidcrosshead only when the knife has reached a predetermined lengthwiseposition with respect to said crosshead.

4. In a cloth cutting machine, a power driven crosshead adapted to bereciprocated, a reciprocatory knife having an elongated slot at one endthereof bounded by a pair of spaced prongs, one of said prongs having aseries of rack teeth extending inwardly therefrom, a knife clampingscrew member threaded into said crosshead, and a pinion on said screwmember adapted to mesh with said'rack teeth whereby upon rotation ofsaid screw member said knife will be moved lengthwise until said pinionlies in the base portion of said slot, the bottom tooth beingsufficiently spaced from the base of said slot whereby said pinion willbe freely rotatable in the base portion of said slot to permit theclamping of the knife in position.

5. A cloth cutting machine including a crosshead adapted to bereciprocated, a reciprocatory knife having a pair of prongs at one endthereof forming an elongated slot extending lengthwise thereof, one ofsaid slots having a series of inwardly extending rack teeth, a screwmember passing through said slot-for locking said knife to saidcrosshead, said screw member having a head, and a pinion at the innerside of said head, said pinion being adapted to mesh with said rackteeth and having a maximum diameter substantially equal to the distancebetween the bases of said teeth and the opposite side of said slot, thebottom rack tooth being sufliciently spaced from the base of the slot toform an opening in the base portion of said slot sufficiently large topermit the free rotation of said pinion therein.

6. As anew article of manufacture, a reciprocatory knife blade for usein a power driven cloth cutting machine, said blade having an elongatedslot extending lengthwise thereof at one end and forming a pair ofspaced prongs for receiving a clamping screw therebetween, one of saidprongs having rack teeth along the inner edge therefrom.

'7. As a new article of manufacture, a reciprocatory knife blade for usein a power driven cloth cutting machine, said blade having an openendedelongated slot extending lengthwise thereof at one end. and forming apair of spaced prongs for receiving a clamping screw therebetween, oneof said prongs having rack teeth extending inwardly therefrom, thebottom tooth 10 to the distance between the bases of said teeth 15 andthe opposite side of said slot.

MARTIN ZAWISTOWSKI.

